With the development of technology, the operation interfaces for various electronic devices are getting more user-friendly in recent years. For example, by using a touch panel, the user may operate a screen or input a message/text/pattern on the screen with a finger or stylus, thereby saving the user the trouble of using an input device such as a keyboard or buttons. Generally, a touch screen is composed of a sensing panel and a display disposed behind the sensing panel. The electronic device recognizes a touch event according to the location of the user's touch on the sensing panel and the screen content displayed at the time of the touch, and executes an operation result correspondingly.
Mutual-capacitance sensing has been widely applied in electronic devices with the touch screen. With the advancement of technology and in response to the market demand, touch screens (such as flexible screens) with ultra-thin protective layers have been developed. However, for a touch screen having ultra-thin protective layers, coupling capacitance between a receive electrode (or a transmit electrode) and the finger is greater, making it more difficult to employ mutual-capacitance sensing. Further, a baseline current flowing through the receive electrode and a ground terminal exists no matter whether a touch event occurs or not, and such baseline current affects a detection result outputted from a capacitance detection circuit. Therefore, the dynamic range of an analog-to-digital converter (ADC) located at the back end of the capacitance detection circuit cannot be effectively utilized, but rather reduces the accuracy of the touch determination.
In view of the foregoing, there is a need for improvement in the related art.